Question

An op-amp circuit is shown below (assume ideal op-amp)

The output voltage for an input $V_i=[2+sin(100t\left)\right]$ V is $V_0$ = A sin (100 t). The value of A is

• A. 1.5

Answer 1

The correct option is A 1.5
Applying Superposition principle
Output due to $-2V$, input signal is

$V_{01}=-2\left(\frac{R}{R+R}\right)(1+\frac{2R}{R})=-3V$

Output due to $V_i$ is

$V_{02}=(2+sin100t)\left(\frac{R}{R+R}\right)(1+\frac{2R}{R})=\frac{3}{2}(2+sin100t)$

Overall output voltage, $V_0=V_{01}+V_{02}=-3+3+\frac{3}{2}sin100t=\frac{3}{2}sin100tV$

Hence, $A=\frac{3}{2}=1.5$